Astrology and its interpretation is built up in a series of layers. The elements form the foundation layer. When looking to interpret or understand the make-up of a birthchart, the elements play an important role in determining the basic character type and the general approach to life. Whichever element dominates by the planetary placements describes the general temperament or disposition. This is the foundation on which to build up the full picture.

The elements are also known as the triplicities, as there are three signs belonging to each and it is between signs of the same element or triplicity that the easy-flowing TRINE aspect comes from. The reason for this is that those signs have a likeness in basic character.

The ten planetary placements are noted as to which of the elements they are in by sign. The element with the most planets posited within would be the more dominant one and therefore the basic character would be read as such. The planets placed within these elements would take on some of the characteristics of them. If two or more elements have equal planetary placements, then they will be combined. Although the Ascendant is not counted regarding elements, it is nevertheless of interest in the general basic make-up. It can also be used to weigh the balance where two or more elements are dominant. A balance between all the elements is the ideal but will rarely be found. Often there is one basic element lacking and it is by other means that a compromise needs to be found. Perhaps a planet by its strength may compensate in some way. An excess of a particular element is in need of being tempered.

The four elements are also known as the four humours. Each relates to a type of person and their basic make-up. This is particularly used in Medical Astrology to provide a holistic basis for treatment. The four humours are also used in Astro-Meteorology to describe a type of wind and in other matters to do with the weather.